Many emollients used widely in personal care compositions are derived from vegetable and/or animal matter. One such example is squalane. Squalane is an emollient which can be derived from a variety of plant and animal sources. It is often used in personal care compositions as it is an effective emollient. The emollient effect, as well as the fact that the compound is stable, i.e., it is not prone to oxidation, makes squalane a desirable ingredient for use as an emollient in personal care compositions including moisturisers, dry skin treatments, oily skin treatments, anti-aging creams and eczema treatments.
Squalane is a saturated form of squalene which is found in human sebum produced in the sebaceous gland and excreted up to the skin's surface from hair follicles, and which contributes to skin waterproofing, innate immunity and elasticity. Therefore, squalane is also a useful emollient for use in personal care products for sensitive skin, because the structure of the compound is so close to that of the naturally-occurring squalene.
The supply of squalane derived from natural sources, particularly vegetable squalane, depends on the availability of the natural source. This puts a limit on the amount of naturally derived squalane available for use. A lot of naturally derived squalane is derived from olive oil. The variable supply of olive oil means that the supply of naturally derived squalane for use in personal care products is also variable, and cannot be relied on.
As a result of the supply issues with naturally derived squalane, formulators are looking to use other emollients in personal care products. However, other emollients are not as stable as squalane, and thus the products lack the effectiveness of squalane-containing products.
There exists a need for an alternative to naturally derived squalane which delivers both the same or a greater level of stability as that seen in samples of naturally-derived squalane.
Synthetically derived compositions which aim to mimic naturally occurring materials are often based on branched fatty acids, as these are often liquid at room temperature and easy to work with, without the disadvantage of being unstable. Commercially available branched fatty acids such as isostearic acid, are obtained as a by-product of the catalytic or thermal dimerisation of unsaturated straight chain fatty acids. Isostearic acid is produced by heating oleic acid in the presence of catalyst, generally clay, to produce dimer, trimer and higher oligomer acids. But instead of polymerising, a portion of the oleic acid rearranges to give a branched, monomeric fatty acid which can be isolated by distillation and hydrogenated. This saturated branched monomeric fatty acid is a mixture of various linear and mainly branched, both monobranched and polybranched, saturated acids which is known as isostearic acid.
Isostearic acid exhibits better stability to oxidation than oleic acid, and is a very useful product which is sold into a wide range of application areas including cosmetic applications.
We have discovered that monobranched fatty acids can have significant advantages over polybranched fatty acids. The prior art is silent with regards to monobranched and polybranched fatty acids, compositions containing a high concentration of monobranched fatty acids and a low concentration of polybranched fatty acids, and their use in the production of emollients.
It is an object of the present invention to address at least one of the disadvantages associated with the prior art.